(CNN) -- Pilots of the Air France flight that crashed in 2009 and plummeted 38,000 ft in just three minutes and 30 seconds, lost vital speed data, France's Bureau of Investigation and Analysis (BEA) said Friday.

Pilots on the aircraft got conflicting air speeds in the minutes leading up to the crash, the interim reports states.

Air crash investigators at the Paris-based BEA have been working on the theory that the speed sensors, known as pitot tubes or probes, malfunctioned because of ice at high altitude.

Since the accident, Air France has replaced the pitots on its Airbus fleet with a newer model.